| A | B |
|---|
| ecology | Study of interactions among organisms and their environment. |
| abiotic factor | Nonliving parts of the environment. |
| biotic factor | Living parts of the environment. |
| population | All members of one species in the same place at the same time. |
| community | Populations of different species that interact in some way. |
| ecosystem | All communities in an area and the abiotic factors that affect them. |
| biosphere | All the ecosystems on Earth. |
| population density | Number of individuals in a population, in a specific area. |
| limiting factor | Any biotic or abiotic factor that limits the number of individuals of a population. |
| symbiosis | Close interaction between two or more different species. |
| habitat | The place where an organisms lives. |
| niche | The role or job of an organism in the ecosystem. |
| food chain | A simple model of the way energy, as food, passes from one organism to another. |
| food web | A series of overlapping food chains that exist in an ecosystem. |
| water cycle | Movement of heat energy around the biosphere. |
